Exercise bike



FIG. 1 is a perspective view of an exercise bike showing my new design;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a left side view thereof;

FIG. 5 is a right side view thereof;

FIG. 6 is a top view thereof; and,

FIG. 7 is a bottom view thereof.

The broken line showing of an exercise bike is included for the purpose of illustrating portions of the article and forms no part of the claimed design. 

CLAIM The ornamental design for an exercise bike, as shown and described. 